Validation of a capillary-driven fragmentation model during mixed columnar-equiaxed solidification with melt convection and grain transport
Research output: Contribution to journal › Article › Research › peer-review
Standard
In: Materialia, Vol. 23.2022, No. June, 101462, 06.2022.
Research output: Contribution to journal › Article › Research › peer-review
Harvard
APA
Vancouver
Author
Bibtex - Download
}
RIS (suitable for import to EndNote) - Download
TY - JOUR
T1 - Validation of a capillary-driven fragmentation model during mixed columnar-equiaxed solidification with melt convection and grain transport
AU - Rodrigues, Christian M.G.
AU - Wu, Menghuai
AU - Zhang, Haijie
AU - Ludwig, Andreas
AU - Kharicha, Abdellah
N1 - Publisher Copyright: © 2022
PY - 2022/6
Y1 - 2022/6
N2 - A mixed columnar-equiaxed solidification model was recently extended to capture the capillary-driven fragmentation phenomenon, which was considered the only mechanism for the formation of equiaxed crystals. The purpose of the present study was to validate the model by replicating a laboratory experiment on the solidification of an aqueous ammonium chloride solution (Gao and Wang, 1999). The experiment was performed by cooling the solution in a vertical test cell from the top surface to allow columnar dendrites to grow. Owing to the fragmentation of the downward-growing columnar dendrites, equiaxed fragments appeared, sedimented, and created a bed of crystals at the bottom of the cell. This pile-up of crystals ultimately met the columnar-tip front coming from the top, thereby leading to a structural transition (columnar-to-equiaxed transition). This experiment was successfully reproduced numerically for the first time, which involved coupling between the following phenomena: fragmentation, melt convection, grain transport, a pile-up of equiaxed crystals, and the potential growth of columnar dendrites from a bed of equiaxed crystals (equiaxed-to-columnar transition). A satisfactory agreement was achieved between the simulation and experimental results. Knowledge about capillary-driven fragmentation was strengthened by analyzing the microstructural evolution. Alloy-dependent parameters Ss0, K0, and a that govern dendrite coarsening and fragmentation were proposed for an aqueous ammonium chloride solution. Finally, the limitations of the current version of the fragmentation model were discussed.
AB - A mixed columnar-equiaxed solidification model was recently extended to capture the capillary-driven fragmentation phenomenon, which was considered the only mechanism for the formation of equiaxed crystals. The purpose of the present study was to validate the model by replicating a laboratory experiment on the solidification of an aqueous ammonium chloride solution (Gao and Wang, 1999). The experiment was performed by cooling the solution in a vertical test cell from the top surface to allow columnar dendrites to grow. Owing to the fragmentation of the downward-growing columnar dendrites, equiaxed fragments appeared, sedimented, and created a bed of crystals at the bottom of the cell. This pile-up of crystals ultimately met the columnar-tip front coming from the top, thereby leading to a structural transition (columnar-to-equiaxed transition). This experiment was successfully reproduced numerically for the first time, which involved coupling between the following phenomena: fragmentation, melt convection, grain transport, a pile-up of equiaxed crystals, and the potential growth of columnar dendrites from a bed of equiaxed crystals (equiaxed-to-columnar transition). A satisfactory agreement was achieved between the simulation and experimental results. Knowledge about capillary-driven fragmentation was strengthened by analyzing the microstructural evolution. Alloy-dependent parameters Ss0, K0, and a that govern dendrite coarsening and fragmentation were proposed for an aqueous ammonium chloride solution. Finally, the limitations of the current version of the fragmentation model were discussed.
KW - Alloy solidification
KW - Fragmentation
KW - Microstructural transition
KW - Model validation
KW - Remelting
KW - Volume-average model
UR - http://www.scopus.com/inward/record.url?scp=85132438164&partnerID=8YFLogxK
U2 - 10.1016/j.mtla.2022.101462
DO - 10.1016/j.mtla.2022.101462
M3 - Article
AN - SCOPUS:85132438164
VL - 23.2022
JO - Materialia
JF - Materialia
SN - 2589-1529
IS - June
M1 - 101462
ER -